dtdw: Did you mean the flash bracket? The thing that holds the microphone up so it is at the same level as the external LCD? Is it this?

Sony VCT-55LH bracket from http://mhohner.de/sony-minolta/flashcomp_acc.php.

The external microphone uses a standard ISO cold shoe (cold shoe = no pins, hotshoe = has pins to trigger flash).

However, it comes with an adapter to mount on the Alpha cameras. The Alpha's flash hotshoe is known officially in manuals as the "Auto-lock Accessory shoe" (though over at Dyxum we'd call it the iISO hotshoe.)

The NEX-C3/3/5 flash hotshoe is called the Smart Accessory Terminal while the NEX-5N uses the Smart Accessory Terminal 2 (with a hole to fit the extra peg on the FDA-EV1S electronic viewfinder.)